I saw even some slightly crazy studies where they launched a shielded probe & high thrust for a very close Solar flyby to achieve crazy high delta-v via Oberth effect so that the probe can catch the next unannounced extrasolar asteroid.
Do you have links for these studies? This sounds very interesting, I've been trying to figure out how we could be ready for this kind of thing. I envision some sort of craft that has a combustion engine on it that uses frozen hydrocarbons present on such a body to power the craft long beyond the life span of solar or nuclear power sources to continue sending data as it leaves the solar system.
Jupiter flyby first that drops the perhelion to 3 solar radii (!) and the a high thrust SRB burn for maximum Obert effect on reaching perhelion. Looks like it can give you up to 70 km/s of delta-v. :)
